Nodes

A node is the basement for the higher-order structure.

The management of the list in the model is done by means of selectting the menu option Node of the menu Structure of the menu Model.

Nodes

This dialog allows creating a new node (New button), modifying an existing node (Edit button) or deleting an existing node (Delete button).

Defining a new node

To create a new node you must set the identifier of the object (which must be a possitive integer different than zero and different than the identifier of any existing object), and the point where the node is defined.

Nodes

Optionally, you can define the sources or the boundary conditions applied to the node.

List of sources

The forces applied to the node match the existing sources in the domain. These sources can be used in any of the equations to solve:

Index Variable Equation

1

Momentum Conservation Equation

2

Pressure Equation

3

Energy Balance Equation

The applied sources can be a prescribed velocity, a prescribed pressure or a prescribed temperature, which match a Dirichlet boundary conditions type.

On the other hand, the boundary contions can match flow type boundary conditions that correspond to Neumann boundary conditions.

The boundary conditions of Dirichlet type can be specified in direct mode: establishing the prescribed value for the variable (velocity, pressure, etc.) at every node.

The boundary conditions of Neumann type can be specified calculating the total flow in the edge of the element where these type of boundary conditions are applied, and pondering this value between the nodes in the edge of the element.

Boundary conditions of Neumann type in the energy equation

1.  Specification of the thermal flow in one of the edge of the element.

The flow equation is defined by

Where n is the normal to the edge where the Neumann boundary conditions is to be applied.

The boundary condition to apply in the edge of the TRIA element is defined by

Where Γ represents the length where the flow is applied, and q the prescribed flow.

2.  Specifying the heat transfer by convection

The flow equation is defined by

Where,

Ta   Ambient temperature

n normal to the edge where the Neumann boundary condition is applied

hc   Convection coefficient

The boundary condition applied at the edges of the TRIA element is defined by

List of constraints

The boundary conditions can be applied at every variable that are simulated according to the rules defined in the following table:

Modifying an existing node

Modifying an existing node can be done by selecting the Edit button of the List of node dialog box. The only non-modifiable field is the object identifier. The rest of fields can be modified as when creating a new node.